I trimmed the excess material off the front of the engine skid plate and got started on the transmission cross-member and skid plate yesterday. I ended up with a pretty big lip between the back of the engine skid plate and the front of the transmission skid plate which could be a hang-up If I got caught on something and needed to back out. Conveniently the piece of material I cut off the front of the engine skid plate was the perfect size to fill the gap, so I welded it to the back of the skid plate. There is still a small little mismatch, but it's a heck of a lot better than it was!

After speaking with a number of axle shops, it's evident that the one double offset inner joint I got from the junkyard was a fluke. It was an aftermarket axle and every OEM and aftermarket joint I can find have tripod joints. One of the shops I spoke with was CVJ axles, who mrdeye connected me with. CVJ hooked me up with some Porsche 930 inner CV joints, which can handle big power and up to 28* of angle and stay happy. These are what pretty much all off-road racing and sand rail guys are using.

The 930 joints have a completely different bolt pattern from the auto trans, so they have to be adapted. I designed a set of adapters and machined them from 2024 aluminum (very high tensile strength). These were done using a manual lathe and mill.

Raw material: 6" round by 1.5" thick

turned to shape:

milling:

Done with milling, drilling & tapping:

Then back on the lathe to take out the center. Here is the finished product along with the drawings:

And here is how they install on the car with the 930 joint.

The 930 joint is 108mm, which is the same outside diameter as the joints on a B5 S4 or a B5 FWD 1.8T Passat. In trying to get some axle shafts with the right splines to fit them, I have ordered every shaft RockAuto and Oreiley's sell for those applications and none of them fit. It seems the aftermarket axle companies use whatever spline they want because I've struck out with every one. With that, it seems unlikely I'll be able to prototype my axles and test drive the car before ordering custom shafts.

Here is a comparison of the S4 CV and the 930. They are the same diameter but the 930 is deeper and allows for more plunge and 8* more articulation:

Last edited by the german on Fri Jun 16, 2017 12:23 am, edited 1 time in total.

Great news: I got a Porsche axle shaft that fits my CVs!! Big shout out to John Walker @ John Walker Workshop, a local old school Porsche/hot rod shop in Seattle. I told John what I was doing and he dug an axle out from under a work bench and gave it to me. Thank you John!

The Porsche axle has the correct spline on both ends so I can use one shaft to make both axles I need. With that in hand I was able to do some measuring and figure out how much longer I wanted to make my lower control arms. I think with 1.5" longer than stock I will be in reasonable territory on the axles to not hurt the inner CV at full droop... or at least close.

I welded up the first lower control arm tonight, and have one more to go tomorrow morning. Here is some more fabrication porn for you all

I welded up and painted the second extended control arm this morning. On the first one I debated putting a brace between the mounting points, but decided I still wanted these to be the mechanical fuse if I hit something hard again, so I left it out. For the second one I made I put the bracing piece in there so that I can try out both designs and see if I like one better in use. It's easy to add/subtract that tube depending on which one I decide I like better.

With those done, I pressed bushings into them and threw them on the car. They both slotted right in easier than the stock stamped ones, look a whole lot better, and should be a good bit stronger too.

With the control arms on I took the springs off the struts so I could run the suspension through it's full range and look for any issues, as well as measure the required plunge depth of the axles. I ended up with needing just under 1" on the driver's side and ~.75" on the passenger side. The 930 CV's are rated at 1.1" of plunge, so I should be in good shape there. I also measured the axle angle at full droop on the driver's side, and it looks like it will end up right about 29-30*. The published limit for the 930 joint is 28*, but the axle shops tell me they will actually do about 30* so hopefully I'll be OK there and won't have to run limiting straps.

I took the cast control arms that were displaced from the front and installed them on the rear, so I am now rid of all the stamped steel ones. Woohoo!

And finally, I chopped my Porsche axle shaft in half in preparation for welding up the my hybrid shafts. I'll pick up the material for sleeving them on Monday, so hopefully Monday night will be the first test-drive with this engine and trans.

Last edited by the german on Sat Jun 17, 2017 11:16 pm, edited 1 time in total.

Your control arms came out looking the business. How much for stock Cq fronts? haha... half kidding.

I like how you opted to experiment on either side with the control arm bracing. Having a sacrificial joint makes sense... that's what Audi did with the stamped control arms and the cast engine/trans/diff mounts. On the other hand, having them as stiff and strong as possible also has its benefits. Might as well use them and see what performs better, and why, before you commit to one design over the other.

Well, you guys are right. That post does make it look way more effortless than it actually was since I left out all the details of how I got to the point of being ready to weld them up. Not shown are the hours of measuring, designing the arms, making the welding fixture, machining parts, three attempts at bending the tubes before getting it right, and then finally cutting and fitting the tubes so that I could weld them.

I don't have a mandrel bender, but my office is right next to a big fishing port/marina (where all the "Deadliest Catch" boats are from), so there is a huge marine industry built up around there. I've made friends with a fabricator at one of the full-service marine maintenance/repair/outfitting businesses which has a really nice shop w/ lots of cool fabrication toys. He is the one who bent the tubes as well as the trans skid plate.

After I test these and make sure everything is good to go, I have the material to make one spare set of control arms then I think I'm done

Last night I polished the races of the inner CVs as the buggy guys say to do this to improve performance and get slightly more angle from the CV's. Before polishing the un-greased joints would bind up pretty easily, but after they moved quite freely. Here is the factory finish vs. polished:

Today I machined the axle shafts and sleeves, and welded them up. I machined a 1/2" deep counter bore in the Audi axle half, which the Porsche axle half slips into. I then machined a sleeve to fit over those two shafts for added reinforcement. The process here is to first weld the two axle halves directly together, then slide the sleeve down over the welded joint and weld it on each end. To keep everything square, I put it all in my hydraulic press with a ball bearing on top and bottom. My thinking here is that it would keep everything forced together square during welding and keep the shafts as straight as possible. I have never seen anyone do this before, but it seemed to work quite well.

The shafts took nearly an hour to cool after welding. Once cool, I assembled the joints and boots onto them, installed them in the car, and took it for it's first drive with the new engine and transmission!

A few observations:1. The car is MUCH faster than it was before. 2. Turbochargers are awesome.3. The transmission is doing some funny things (harsh engagement into gear, hanging onto gears for a long time, tiptronic mode not working)4. One/some of the front CV joints is clicking5. I killed both inner front CV boots before the car even moved. At full droop, the axle shaft hits the metal part of the CV and deforms it, which in turn causes the boot that is clamped onto it to pop off. 6. Something is not quite right with the cooling. In my puttering around it got one tic above thermostatic temp and took a long time to come back down.7. I need to add ARB provisions to the front control arms. The road manners when cornering are severely affected by it's absence.8. I need to add camber bolts to the strut housings to correct camber after installing the extended control arms.

Jim - funny you mention that, I just ordered a set! With any luck they will be here Saturday.

I called several axle places today and they all say I shouldn't have a clicking issue with the new joints at the angles I'm running. Going to tear it back apart tonight to inspect and look for the cause.

Well- I feel like a big dumb dumb. After striking out on finding double offset CVs for the automatic axles and being told by all the axle guys that I should run 930 joints, I just went with it and didn't even think to measure what the stock coupe joints would do. On a lark, I measured them tonight and they do 28* angle and 1.75" (!!!) of plunge. I should have just been using those all along!

Yesterday I welded in a new cross-piece on the right side of the lift subframe to replace the one I cut out making room for the axle. Today, my high-angle CV boots for the 930 joint came in and they fit great. When I installed these I also swapped out the right front outside CV joint as I suspected that was the one that was clicking on my previous test drive.

I went for an extended test drive this evening, including some freeway driving, and overall it drives nicely and is much quicker than it was with the 7a. There is no longer any CV clicking and the transmission also seemed to be behaving it's self much better than it did the other day. I did some trouble shooting on the running hot issue and it appears I have a bad temperature switch in the radiator as the fans aren't running at all when it's above temp, but they kick on if I jump the terminals at the sensor connector. Easy enough to fix and I can just jump it and let them run all the time while I wait for the replacement part to arrive.

I measured the 930 joints I have and the only give me .6" or plunge and 22* articulation rather than the 1.1" and 28* that some versions advertise. This is not enough for my setup. I machined my axle adapters with the pattern for the 100mm stock inner CQ CV's so I now have the option of running either joint. I re-purposed my old axle spacers and turned them into high-angle boot holders so I can run a similar setup on those as the new 930 boots I got today. I think this will be my best option and still gives me lots of flexibility if I run into issues getting joints.

Finally, I have some work to do on making it so the car will align properly after installing the extended control arms. There was plenty or room to adjust toe correctly but I'm pretty "stanced" with about 5.5* of negative camber at static ride height. I have some parts on order to deal with this, which will use a combination of BMW factory and aftermarket parts with some light fabrication.

I also have some fancy aftermarket Jeep sway bar links on order which should give a pretty trick set up for the front ARB. More to come later, but for now, it's good enough for the Audi Expo on Saturday!

Well, I lied when I said "good enough for Audi Expo". I though it was good to go, but after work I took it to run some errands and only made it about a mile from my house before I broke it. I bounced the car bombing over a row of speed bumps and in doing so I unloaded the suspension enough to pull the RF axle shaft out of the outboard CV. This renders the car immobile, so I had to walk back home, load the floor jack in my S4, drive back to the CQ, lift it up and put the axle shaft back in the CV, drive it home, ride my bike back to pick up the S4, then finally go run my errands.

I removed the whole RF axle to inspect it, and it was clear there is just not enough plunge in the 930 joints for this setup. I then initiated "Plan B", which was a new (shortened) set CQ axle shafts and joints. Good thing I preemptively drilled and tapped the adapters with the 100 mm pattern the other day and ordered some boots to fit them!

To make the new shafts I cut the stock axles in half, bolt them in the car then run the suspension through it's range to determine length for each. I had to drive back into work to machine them (good thing our shop runs 24/7), then bring them home to weld, assemble, install, and test-drive.

Scrapped 930 shafts:

New shafts cut & machined:

First stage of welding done:

Welded, assembled, installed:

With this setup both front tires can sit at full droop and turn freely without binding and there is no danger of pulling a shaft out of the CV due to the added plunge depth I picked up. That's what I was looking for! It took me until just after 3:00 AM to get this far (two hour break to let the axles cool after welding- you want that process to go nice and slow to reduce internal stress and keep maximum strength).

OK- now we are ready to go to Audi Expo! maybe.

An hour before I planned to leave I did a little test staging of the car with one tire up on a log, and it looked pretty good. Then I backed the car out, articulated it weird while turning out of my driveway, bound up the right front inner joint, and shattered the bearing cage.

Super. Duper. Good thing it has a winch to pull it's self back into the garage.

Cue the mad rush to pull the axle, replace the joint (with my last one) and get it all back in the car. Got that done in about 30 minutes so I guess all this practice is paying off. LOL

OK, now it's ready for real this time. My wife drove the lifted car and I followed in my V8 swapped CQ. Car ran flawlessly on the 1 hour drive and I got some special parking on the lawn with the rally cars.

I'm sure some other folks got better pictures (please post them if you do!) but here are the few I took:

Obligatory Sport Quattro rally car photo:

Right as we got close to home, the car started misfiring and running rough. My wife limped it home and I'll dig into that with VAG-COM later. Now it's time for some sleep after a good long day.

Last edited by the german on Sun Jun 25, 2017 2:55 pm, edited 1 time in total.